摘要:

AbstractThe synthesis of (±)‐[1,1′‐15N2, 2′‐13C]‐trans‐3′‐methylnicotine is reported.15N‐3‐Bromopyridine obtained from bromination of pyridine was formulated with nBuLi/[carbonyl‐13C]‐methyl formate. The resulting15N‐Pyridine‐3‐[13C‐carbonyl]‐carboxaldehyde was reacted with15N‐methylamine and then the resulting Schiff's base was condensed with succinic anhydride to give (±)‐[1,1′‐15N2, 5′‐13C]‐trans‐4′‐carboxycotinine. Reduction with lithium aluminium hydride and mesylation followed by reduction with Zn

ISSN:0362-4803    

DOI:10.1002/jlcr.2580310302

出版商:John Wiley&Sons, Ltd.    

年代:1992

数据来源: WILEY

摘要:

AbstractAcifluorfen1and acifluorfen methyl2, two herbicides of the diphenylether family, are inhibitors of protoporphyrinogen oxidases. Two tritiated derivatives of these compounds, namely 3‐[3H]‐5‐[2‐chloro‐4‐(trifluoromethyl)phenoxy]‐2‐nitrobenzoic acid [3H]‐1, and methyl 3‐[3H]‐5‐[2‐chloro‐4‐(trifluoromethyl)phenoxy]‐2‐nitrobenzoic acid [3H]‐2, have been synthesised from 3‐[3H]‐5‐hydroxybenzoic acid, in order to probe t

ISSN:0362-4803    

DOI:10.1002/jlcr.2580310303

出版商:John Wiley&Sons, Ltd.    

年代:1992

数据来源: WILEY

摘要:

AbstractSynthesis of a [13C] tetrapeptide L‐[U‐13C]Lysyl‐L‐[1‐13C]Arginyl‐L‐[3‐13C]Aspartyl‐L‐[1‐13C] Serine (KRDS) on ap‐alkoxybenzyl ester polystyrene‐1% divinylbenzene resin support is described by using repetitive nonhydrolytic base cleavage of α‐amino protective groups in Solid Phase Peptide Synthesis (SPPS). Protected [13C] amino acid (AA) used in this SPPS model were prepared with 9‐Fluorenylmethyloxycarbonyl (Fmoc) protecting group and with different acid labile side chain protecting group over AA type as: Fmoc‐Ser(tert‐Bu)‐OH, Fmoc‐Asp(tert‐Bu)‐OH, Fmoc‐Arg(Pmc)‐OH and Fmoc‐Lys(Fmoc)‐OH. All the protected AA were coupled byN,N′‐dicyclohexyl carbodiimide (DCC) procedure, followed by Fmoc group cleavage using 20% piperidine inN,Ndimethylacetamide (DMA). Quantitative deblocking side‐chain AA protection and removal of KRDS from the solid support was effected by treatment with 50% trifluoroacetic acid in methylene chloride in a one pot‐procedure. Homogeneous free [13C] KRDS was obtained in 90% overall yield after HPLC purification. This synthesis schedule offered the advantage over present solid phase method whi

ISSN:0362-4803    

DOI:10.1002/jlcr.2580310304

出版商:John Wiley&Sons, Ltd.    

年代:1992

数据来源: WILEY

摘要:

AbstractDebutanoylthapsigargin (2) labelled in the skeleton was prepared by stereoselective reduction of the ketone (3) obtained by oxidation of debutanoylthapsigargin. Butanoylation of2yielded thapsigargin1. The use of sodium boro[3H]hydride as a reducing agent afforded labelled debutanoylthapsigargin with a specific activity of 22 Ci/mmol.A fluorescent analogue of thapsigargin (4a) was prepared by allowing2to react with N‐dansyl‐β‐alanine. Acetylation of4aafforded a trisacetate (4c) the missing bioactivity of which allows it to be used as a negative c

ISSN:0362-4803    

DOI:10.1002/jlcr.2580310305

出版商:John Wiley&Sons, Ltd.    

年代:1992

数据来源: WILEY

摘要:

AbstractAdvantages of using a microwave cavity over thermal treatment are demonstrated for radiolabelling reactions with [11C]cyanide. For comparison purposes, two literature syntheses involving typical cyanide chemistry at rather vigorous conditions were investigated: cyano‐de‐halogenation with subsequent hydrolysis of the nitrile and the Bücher‐Strecker synthesis of an aromatic amino acid. Comparable yields were obtained with intensities<100 W in reaction times that were 1/15 to 1/20th those used in thermal methods. Even rates of slower nucleophilic substitutions could be increased by manipulating the polarity of the medium. For the short‐lived radionuclide carbon‐11, such time gains result in radioactivity gains at the end‐of‐synthesis on the or

ISSN:0362-4803    

DOI:10.1002/jlcr.2580310306

出版商:John Wiley&Sons, Ltd.    

年代:1992

数据来源: WILEY

摘要:

AbstractAn123I labeled cocaine analog, 4′‐[123I]iodococaine, has been prepared by oxidative destannylation of the tributyltin analog and shown to interact with cocaine binding sites in rat brain striatal membranes. It may thus be a suitable SPECT radiotracer for studies of the dopamine reuptake site in neurodegenerative disea

ISSN:0362-4803    

DOI:10.1002/jlcr.2580310307

出版商:John Wiley&Sons, Ltd.    

年代:1992

数据来源: WILEY

摘要:

AbstractTritiated dextran and inulin were prepared by both a catalytic solid state and a liquid phase isotope exchange with gaseous tritium. The liquid phase procedure is convenient for preparation of the polysaccharides with specific activities up to 5 mCi/g, while the solid state procedure allows specific activities up to 700 mCi/g.

ISSN:0362-4803    

DOI:10.1002/jlcr.2580310308

出版商:John Wiley&Sons, Ltd.    

年代:1992

数据来源: WILEY

ISSN:0362-4803    

DOI:10.1002/jlcr.2580310301

出版商:John Wiley&Sons, Ltd.    

年代:1992

数据来源: WILEY